Linux is evolving as the predominant operating system of the new millennium, and legacy operating systems such as OS/2 are being gradually phased out. This series of articles helps the developers involved in the tedious process of migrating/porting the OS/2 system drivers and applications to Linux. In this last of three installments, the authors focus on how to do timer calls and DLL calls in OS/2 and Linux, with a view to mapping between the two systems.